Science Briefs

Lowland South America, including the Amazon Basin, harbors most of the last indigenous societies that have limited contact with the outside world. Studying these tribes, located deep within Amazonian rainforests, gives scientists a glimpse at what tribal cultures may have been like before the arrival of Europeans. Now, researchers at the University of Missouri have used satellite images to assess the demographic health of one particular village of isolated people on the border between Brazil and Peru. Remote surveillance is the only method to safely track uncontacted indigenous societies and may offer information that can improve their chances for long-term survival.

Rob Walker, a University of Missouri anthropologist, and Marcus Hamilton, an anthropologist at the University of New Mexico, used Google Earth satellite imagery to estimate the area of the fields and the size of the village belonging to the tribe, as well as the living area of the tribe’s temporary housing, and compared that with similar estimates for 71 other Brazilian indigenous communities.

“We found that the estimated population of the village is no more than 40 people,” Walker said. “A small, isolated village like this one faces an imminent threat of extinction. However, forced contact from the outside world is ill-advised, so a non-invasive means of monitoring the tribe is recommended.” missouri.edu

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Scientists have conclusive evidence that the source of a unique rhythmic sound, recorded for decades in the Southern Ocean and called the “bio-duck,” is the Antarctic minke whale. First described and named by submarine personnel in the 1960s who thought it sounded like a duck, the source of the sound remained a mystery, until now.

In February 2013, an international team of researchers deployed acoustic tags on two Antarctic minke whales off the western Antarctic Peninsula. These tags were the first acoustic tags successfully deployed on this species. The acoustic analysis of the data, which contained the bio-duck sound, was led by Denise Risch of NOAA’s Northeast Fisheries Science Center and was published in April in Biology Letters .

The bio-duck sound is heard mainly during the austral winter around Antarctica and off Australia’s west coast. Described as a series of pulses in a highly repetitive pattern, the bio-duck’s presence in higher and lower latitudes during the winter season also contributed to its mystery. No one knew the minke whales were there. The identification of the Antarctic minke whale as the source of the sound now indicates that some minke whales stay in ice-covered Antarctic waters year-round, while others undertake seasonal migrations. nefsc.noaa.gov

What male black widow spiders see in a mate

New University of Toronto at Scarborough research shows that male black widow spiders prefer their female mates to be well-fed virgins, revealing a rare example of mate preference by male spiders. The study also found male black widows can tell whether a potential mate is well-fed and unmated by pheromones released by females.

“Females who have been able to eat a lot and obtain a lot of food resources can transfer those resources into egg production,” said Emily MacLeod, a post-doc student and co-author of the study. The research is published in the journal Animal Behaviour. utoronto.ca